ERP Correlates of Altered Orthographic-Phonological Processing in Dyslexia.

Vera Varga,Dénes Tóth,Valéria Csépe,Dávid Czikora,Kathleen Kay Amora

doi:10.3389/fpsyg.2021.723404

Abstract

Automatic visual word recognition requires not only well-established phonological and orthographic representations but also efficient audio-visual integration of these representations. One possibility is that in developmental dyslexia, inefficient orthographic processing might underlie poor reading. Alternatively, reading deficit could be due to inefficient phonological processing or inefficient integration of orthographic and phonological information. In this event-related potential study, participants with dyslexia (N = 25) and control readers (N = 27) were presented with pairs of words and pseudowords in an implicit same-different task. The reference-target pairs could be identical, or different in the identity or the position of the letters. To test the orthographic-phonological processing, target stimuli were presented in visual-only and audiovisual conditions. Participants with and without dyslexia processed the reference stimuli similarly; however, group differences emerged in the processing of target stimuli, especially in the audiovisual condition where control readers showed greater N1 responses for words than for pseudowords, but readers with dyslexia did not show such difference. Moreover, after 300 ms lexicality effect exhibited a more focused frontal topographic distribution in readers with dyslexia. Our results suggest that in developmental dyslexia, phonological processing and audiovisual processing deficits are more pronounced than orthographic processing deficits.

Highlights

Automatic visual word recognition requires well-established phonological and orthographic representations and efficient audio-visual integration of these representations
The above results indicate that in developmental dyslexia, orthographic-phonological processing deficits are more pronounced than orthographic processing deficits per se
Our participants were speakers of a highly transparent language (Hungarian); this could suggest that participants with dyslexia in our study did not have fully automatized grapheme-phoneme mapping, but their decoding is automatic enough due to the shallow orthography of Hungarian so that no lexicality effect could be detected

Summary

Introduction

Automatic visual word recognition requires well-established phonological and orthographic representations and efficient audio-visual integration of these representations. Most children acquire these skills without any problems; around 5–10% of schoolaged children fail to develop age-appropriate reading and spelling skills (Schulte-Körne, 2010; Galuschka and Schulte-Körne, 2016; Barbiero et al, 2019). Skilled adult readers typically exhibit automatic grapheme-phoneme mapping wherein presentation of one code activates the other and vice versa (Harm et al, 2004); in Orthographic-Phonological Processing in Dyslexia readers with dyslexia speech-sound associations may never reach automatization (Vellutino et al, 2004). Phonological dyslexia is characterized by impaired pseudoword reading with relatively normal word reading

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